Direct lift aircraft



July 11, 1950 E. A. STALKER DIRECT LIFT AIRCRAFT Filed Aug. 9, 1946 FIG 1,

4 Sheets-Sheet 1 INVENTOR.

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ATTORNEYS July 11, 1950 a A. STALKER nmsc'r LIFT AIRCRAFT 4 Sheets-Sheet 2 Filed Aug. 9, 1946 INVENTOR. Mam

ATTORNEYS July 11, 1950 5 STALKER 2,514,459

DIRECT LIFT AIRCRAFT Filed Aug. 9, 1946 4 Sheets-Sheet 4 FIG 6.

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QQMMMM AT TURNE Y8 Patcnted July 11, 1950 UNITED STATES PATENT OFFICE 2,514,459 DIRECT LIFT AIRCRAFT Edward A. Stalker, Bay City, Mich. Application August 9, 1946, Serial No. 689,449 6 Claims. (i. 110100.15)

This invention relates to direct lift aircraft.

An object of the invention is to provide correct cyclic pitch control for each blade for a wide range of advance ratios, that is. the ratio of forward speed to tip peripheral speed of the lifting rotor.

Other objects will appear from the description, drawings and claims.

In the drawings:

Fig. 1 is a top plan view of the aircraft constructed in accordance with the present invention:

Fig. 2 is a front elevation of the aircraft:

Fig. 3 is a fragmentary front view of the hub partly in section;

Fig. 4 i a fragmentary section along the line 4-4 in Fig. 1 with the control arms rotated through 90;

Fig. 5 is a sectional view of the three-dimensional cam and associated mechanism;

Fig. 6 is a view along the line 8-6 in Fig. 5;

Fig.7 is a fragmentary section of the control arms along line 1-1 of Fig. 1; and

Fig. 8 is a section along the line 8-8 of Fig. 7.

Fig. 9 is a fragmentary side view of the rotor pitch control actuators partly in section.

Cros reference is made to application Serial The simple swash plate imposes a sinusoidal variation in pitch The present invention discloses a non-arbitrary pitch control. That is, the orbital pattern of pitch control changes with the advance ratio so that each blade is properly varied as to pitch to have the correct pitch setting in each point of its orbit. This is accomplished by providing a group of cam contours to give a group of pitch orbit. These patterns are not determined by any arbitrary mechanical connection between the blades. For instance, they are not all derivable from a sinusoidal relation such as would be the case were they derived from a tiltable swash plate.

The body having this group of contours is referred to herein as a three-dimensional cam. Any one of the contours can be put into ca contact with a contactor contour in contact with the contactor.

The proper contour of the cam is selected automatically in accordance with the advance ratio.

employing a, three-dimensional cyclic control cam. The cam It, as shown in Figs. 4, 5 and 6. has an infinite number of parallel contours A-A to E-E, Fig. 5. The bottom contour E-E is a circle about the axis. At horizontal planes in sucblades through bell crank l9, rod 20, crank 22, and flap torque tube 23 which is directly connected to the flap adjusting mechanism, not shown in detail. A corresponding contactor the opposite side of cam l8 and opposite phase relation thereto.

The contactors cause movements of the flaps prevailing advance ratio. such movement of the flaps produces a change in the eiiectlve pitch 0! the blades similar to that which would be obrods 52 and by 3 tained by bodily rotation of the blade, and is the preferred manner of obtaining the desired change of pitch and of lift of the blade.

The selection of the contour according to the advance ratio of the aircraft is done automatically by the mechanism shown in Figs. 4, 7 and 9. A pair of streamline hollow control arms is are rotatably mounted on shaft 25 which is carried by and in position above the hub II; at their outer ends the blades carry the oppositely facing Venturi openings 2. As will be evident the two venturis during rotation alternately assume advancing and retreating positions. Tubes 21 communicate with the respective Venturi openings and are connected through valve II (Fig. '7) and tubes 30 and ii respectively to opposite sides of piston 32 in cylinder 3!, Fig. 9. As shown, the piston is normally loaded or biased in one direction by means of spring 35. The valve 28 is so constructed that as the control arms 24 rotate, the retreating venturi It always communicates suction to one side of the piston through tube 30 and the advancing venturi it always communicates suction to the other or spring loaded side of the piston through tube Ii. The difference in suction force is carried through rod 86 to the follow-up valve 31 serving the hydraulic jack 38 which in turn moves the earn it axially the proper amount by means of the tubular shaft I through which an operating connection is established. The earn it is stopped at the proper point by the action of rod ll, crank 42 and rod ll attached to the follow-up arm 39 of valve 31.

The jack 38 is supplied with fluid under pressure from some suitable source (not shown) from which it flows via tube H to valve I1 and then to jack 38 by either tube 45 or it to cause selective movement thereof. Fluid returning from the Jack to valve 31 passes to the source via tube 41.

Manual control It laterally and stick (not shown).

is obtained by shifting the cam longitudinally by the pilot's The pilot's stick actuates suitable links and bellcranks in the manner well known in the art. Movement of rod 52 for example is caused by motion of the stick to cause an upward or downward pitch and movement of rod 53 similarly responds to a movement of the stick to cause roll. These rods in turn rotate concentric tubular shafts M and 86 respectively. Gears i8 and it are fastened on the upper ends of the shafts 54 and 56 respectively. These gears mesh respectively with gear sets 62 and 64. There are four gears in each set, each fixed eccentricaliy to a corresponding cam. Cams 63 are fastened by suitable shafts 65 to gears 82, and cams l5 are similarly fastened by shafts 61 to gears 84 as shown in Figs. 4 and 6. The cams all engage in recesses 63a and 68a formed internally of cam it and thus as these small cams are rotated, the large cam I6 is shifted laterally or longitudinally, sliding on plate 68 and top of gear box 6!. Cam It is recessed at the top and bottom to receive the plates 68 and the top plate of the gear box il, respectively.

The small cams BI and GI all bear on the side wall surface of the recesses "a and 68a in the upper and lower faces of the cam It. For longitudinal shifting of cam it only the cams it are rotated, cams I! remaining still. The cams ii are rotated simultaneously through operation of control rod 53 and always keep contact with the the accompanying change 79 contour E-E at the bottom of the cam surface of recesses 88a. Similarly, cams B: bear against recesses "a and under control of rod 5! provide for the lateral guidance of cam Ii. Obviously if cam set 83 is rotated at the same time as 86 the cam 16 moves both laterally and longttudinally.

when the cam it is shifted vertically by action of shaft Ill and lacks 3B, the whole assembly, consisting of shafts 5| and i6, gears 58 and 6B, and the gear box 59, is shifted vertically also. The shaft 56 (Fig. 4) slides in bearing 12 of shaft 13 fastened to hub cage ll while the cam i6 slides on fixed shaft 15 using bearings It. The shaft I5 is attached to frame ll, Fig. 3, and does not rotate.

Tube 40 at its upper end is attached to the cam it by means of a bolt 18 fixed in the tube head "a and passing slidably through a slot 19 in the tube IS.

Referring to Figs. 4 and 6, the cyclic control cam Ni is supported for vertical sliding on the bearings It as already described. These bearings are fixed in the square housing of the cam which is supported between plate 58 and the top of gear box 69 by bolts Bl passing through the four arms Ila, and the spacers Bib. The cam is guided in its transverse motion by the plate Gil fixed to housing 80 and the upper plate of the gear box 69 which is also fixed to housing 80.

The two rotor blades are fastened together rigidly by means of hub fitting B2. The hub fitting is pivoted on the hub cage 14 by pins 84 and 85, thus allowing the blades to flap about their common axis 81-85. The hub cage 14 is supported by shaft 86 in frame 88 (see Figs. 3 and 4) and rotates with the rotor blades around the cam l8 and its supporting shafts. At the top of shaft 15 is fastened a gear 90. Gear 90 meshes with gear 92 of hub cage gear box 94 which in turn drives gear 98. Gear 96 meshes with gear 98 of the control arm shaft 25. Since shaft 15 is stationary while the hub cage rotates, gears 92, 9B and 88 will rotate the streamlined control arms H.

The small shaft 100 inside shaft 25 is fixed at its lower end to shaft 15 by means of threaded insert I04 (Fig. 4). Fixed to the upper end of shaft III! is the stationary half I" of valve 28. The movable half ill! of valve 28 rotates with the control arms as so that the venturi in the retreating position as shown is always connected to the proper section Hi6 of the valve via openings I" (Fig. 8).

It will be understood that the lower half Hit of the valve 28 remains fixed in the aircraft. The valve port I III in I08 on the retreating side of the rotor axis is always connected to tube 3|. Hence, whenever a venturi rotates into the retreating position, opening I09 is made to register with lid. Thus only pressure from the venturi in the retreating position is transmitted through tube iii. In a like mode of operation, tube 30 receives pressure only from a venturi in the advancing position.

Propulsion is accomplished by air jets of large mass expelled through slots ill in the blades l2 extending along the outer 50 or 60 per cent of the radius. The air is inducted from the sides of the fuselage through a peripheral slot H6 by a blower which discharges the compressed air into the rotor hub. It then flows through ducts H8 tipward in the blade to the blade slots.

When the helicopter is hovering in still air the contactor I8 is in contact with the circular ll. As

forward flight is initiated and as the speed of flight increases, the cam ii is shifted vertically to put other contours in contact with the contactor.

When the aircraft begins to ascend in still air the contactors It will be in contact with the lower contour E-E which is a circle as remarked. The blades will then have the same flap settings for all orbital positions. When the airplane experiences a horizontal relative wind, the venturls 26 will transmit different suction effects to the cylinder 34, thus sensing and being responsive to the advance ratio of the aircraft. The advancing venturi will transmit suction via tube ill and the venturi in the retreating position will transmit suction via tube ii. These suctions will determine the position of the piston 32 along the axis of cylinder 34. The movement of the piston 32 will open valve 31 to pass fluid to the Jack 38 which moves shaft 40 and cam l6 vertically. A linkage 4l-|2|3 connecting the shaft 40 to follow-up valve I! will cut oil the flow of fluid at the position of shaft ll determined by the displacement of piston II.

The cam, due to the forward flight of the machine, will take up such a position, for instance, as to put th contactor in contact with contour DD and the pitch of each blade will be varied throughout its orbit because of the cam contour DD which is no longer circular. Since the contour is proper the blades will not see-saw about the axes of the pivots 84 and 85 although free to do so. The tendency to see-saw action of the blades will be effectively suppressed and would come into play only due to some momentary disturbance such as a gust.

It is to be under stood that, during any seesaw action, only the blades and the interconnecting fitting l2 partake of this action. The cage 1| rotates about its vertical axis while cam l6 and its supports are still. The cage I4 carries the contactor it about the cam l6 so that the contactor is moved by the variation in cam contour.

As the aircraft gains greater forward speed the venturis transmit a greater suction difference and cause a further elevation 01 cam It.

If the pilot wishes to make a maneuver, he shifts cam 16 horizontally. This motion is accomplished by the rotation of the small cams '63 for lateral tilting of the plane of rotation of the blades, and by the rotation of the small cams 66 for longitudinal tilting of the plane of rotation of the blades.

It will now be clear that a cyclic pitch control has been provided which can provide different types of cyclic pitch patterns for the moment of a blade about its orbit. By this means the pitch can be correct for all orbital positions and independent of the pitch change being imposed at another point of the orbit. This control largely eliminates the blade forces which cause vibration.

While the form of apparatus herein described constitutes a preferred embodiment of the invention, it is to be understood that the invention is not limited to this precise form of apparatus, and that changes may be made therein without departing from the scope of the invention which is defined in the appended claims.

What is claimed is:

1. In combination in a direct lift arcraft, a blade supported for rotation about an upright axis, means to vary the effective pitch of said blade, a cam having a plurality of closed camming contours, a sensing element engageable with said cam, means supporting said cam and said element for relative rotation and for controlled relative displacements both in the direction of and tranverse to said axis, means actuated by said element to control said itch varying means cyclically in ac? cordance with a said contour of said cam, means to move said cam relative to said element in the direction of said axis to select different contours for engagement with said element, a device responsive to the advance radio of said aircraft, and means operably relating said device and said cam moving means to displace said cam in the direction transverse to said axis in accordance with the change in the advance ratio of said aircraft.

'2. In combination in an aircraft, a blade supported for rotation about an upright axis, means to vary the lift of said blade, a cam having a plurality of closed camming contours, a sensing element engageable with said cam, means supporting said cam and said element for relative rotation and for relative displacement with respect to each other, means for operably connecting said element to said lift varying means to alter the lift of said blade cyclically in response to the shape of a said contour, on the aircraft means responsive to the advance ratio of the aircraft, and means controlled by said responsive means to displace said cam relative to said element to vary the cam contour engaged by said sensing element to establish correct cyclic control of the blade lift for varying advance ratios.

3. In combination in a direct lift aircraft, a blade supported for rotation about an upright axis, means to vary the effective pitch of said blade, a cam having a plurality of closed camming contours, a sensing element engageable with said cam. means supporting said cam and said element for relative rotation and for actuated relative displacements, means controlled by said element to control said pitch varying means cyclically in accordance with a said contour of said cam, means to move said cam relative to said element in one plane to select different contours for engagement with said element, sensing means rotatably mounted on said aircraft to gauge the advance ratio of said blade from the combined effects of rotation and the relative wind, and means responsive to said sensing means to displace said came relative to said element in a plane at right angles to said one plane to vary the cam contour in contact with said element in accordance with the change in the advance ratio of said blade.

4. In combination in a direct lift aircraft, a blade, means supporting said blade for rotation about a vertical axis, a cyclic control cam having a plurality of camming contours, a sensing element controlled by said cam, means supporting said cam and said element for rotation relative to each other. means to control the effective pitch of said blade cyclically according to a pattern determined by engagement of said element with a camming contour of said cam, means for supporting said cam for displacement transversely to said axis, bearing surfaces carried by said cam for guiding said cam in said transverse displacement, a plurality of control cams bearing on each said surface, and means to. rotate said control cams bearing on opposite facing surfaces of said cyclic control cam to displace said cyclic control cam transversely to said axis.

5. In combination in an aircraft, a blade supported for rotation about an upright axis, means to vary the lift of said blade, cyclic control means having a plurality oi control positions, a sensing element rotatable relative to and cooperating with said control means in a selected one of said control positions, means to shift said control means and said element relative to each other in directions at right angles to each other in the plane transverse to said upright axis to establish control of said sensing element in difi'erent control positions, means interconnecting said sensing element and said lift varying means to alter the lift of said blade in accordance with the control of said element by said control means, means responsive tothe advance ratio or the aircraft, and means controlled by said responsive means for actuating said shifting means for establishing a selected one of said control positions.

6. In combination in an aircraft, a blade supported for rotation about an upright axis, means to vary the lift of said blade, cyclic control means having a plurality of control positions, a. sensing element rotatable relative to and cooperating with said control means in a selected one of said control positions, means to shift said control means and said element relative to each other in directions at right angles to each other in the plane transverse to said upright axis to establish control of said sensing element in difierent control positions, means interconnecting said sensing element and said liit varying means to alter the lift of said blade in accordance with the control of said element by said control means, means responsive to the advance ratio of the aircraft. means controlled by said responslve means for actuating said shifting means in one direction to a predetermined control position. and additional means for shifting said cyclic control means relative to said sensing element in a direction at right angles to said one direction to establish a predetermined cyclic control of the lift oi said blade.

EDWARD A, STALKER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,403,624 Pescara Jan. 17, 1922 1,449,129 Pescara Mar. 20, 1923 1,592,740 MacNeil July 13, 1926 2,414,435 Bendix Jan. 21, 1947 2,425,651 Stalker Aug. 12, 1947 2,493,042 Stalker Jan 3, 1950 FOREIGN PATENTS Number Country Date 610,434 Germany Mar. 12, 1935 

